<?php
/**
 * Zend Framework
 *
 * LICENSE
 *
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@zend.com so we can send you a copy immediately.
 *
 * @category   Zend
 * @package    Zend_Queue
 * @subpackage Adapter
 * @copyright  Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 * @version    $Id: Memcacheq.php 18951 2009-11-12 16:26:19Z alexander $
 */

/**
 * @see Zend_Queue_Adapter_AdapterAbstract
 */
require_once 'Zend/Queue/Adapter/AdapterAbstract.php';

/**
 * Class for using connecting to a Zend_Cache-based queuing system
 *
 * @category   Zend
 * @package    Zend_Queue
 * @subpackage Adapter
 * @copyright  Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 */
class Zend_Queue_Adapter_Memcacheq extends Zend_Queue_Adapter_AdapterAbstract
{
	const DEFAULT_HOST = '127.0.0.1';
	const DEFAULT_PORT = 22201;
	const EOL          = "\r\n";

	/**
	 * @var Memcache
	 */
	protected $_cache = null;

	/**
	 * @var string
	 */
	protected $_host = null;

	/**
	 * @var integer
	 */
	protected $_port = null;

	/**
	 * @var resource
	 */
	protected $_socket = null;

	/********************************************************************
	 * Constructor / Destructor
	 *********************************************************************/

	/**
	 * Constructor
	 *
	 * @param  array|Zend_Config $options
	 * @param  null|Zend_Queue $queue
	 * @return void
	 */
	public function __construct($options, Zend_Queue $queue = null)
	{
		if (!extension_loaded('memcache')) {
			require_once 'Zend/Queue/Exception.php';
			throw new Zend_Queue_Exception('Memcache extension does not appear to be loaded');
		}

		parent::__construct($options, $queue);

		$options = &$this->_options['driverOptions'];

		if (!array_key_exists('host', $options)) {
			$options['host'] = self::DEFAULT_HOST;
		}
		if (!array_key_exists('port', $options)) {
			$options['port'] = self::DEFAULT_PORT;
		}

		$this->_cache = new Memcache();

		$result = $this->_cache->connect($options['host'], $options['port']);

		if ($result === false) {
			require_once 'Zend/Queue/Exception.php';
			throw new Zend_Queue_Exception('Could not connect to MemcacheQ');
		}

		$this->_host = $options['host'];
		$this->_port = (int)$options['port'];
	}

	/**
	 * Destructor
	 *
	 * @return void
	 */
	public function __destruct()
	{
		if ($this->_cache instanceof Memcache) {
			$this->_cache->close();
		}
		if (is_resource($this->_socket)) {
			$cmd = 'quit' . self::EOL;
			fwrite($this->_socket, $cmd);
			fclose($this->_socket);
		}
	}

	/********************************************************************
	 * Queue management functions
	 *********************************************************************/

	/**
	 * Does a queue already exist?
	 *
	 * Throws an exception if the adapter cannot determine if a queue exists.
	 * use isSupported('isExists') to determine if an adapter can test for
	 * queue existance.
	 *
	 * @param  string $name
	 * @return boolean
	 * @throws Zend_Queue_Exception
	 */
	public function isExists($name)
	{
		if (empty($this->_queues)) {
			$this->getQueues();
		}

		return in_array($name, $this->_queues);
	}

	/**
	 * Create a new queue
	 *
	 * Visibility timeout is how long a message is left in the queue "invisible"
	 * to other readers.  If the message is acknowleged (deleted) before the
	 * timeout, then the message is deleted.  However, if the timeout expires
	 * then the message will be made available to other queue readers.
	 *
	 * @param  string  $name    queue name
	 * @param  integer $timeout default visibility timeout
	 * @return boolean
	 * @throws Zend_Queue_Exception
	 */
	public function create($name, $timeout=null)
	{
		if ($this->isExists($name)) {
			return false;
		}
		if ($timeout === null) {
			$timeout = self::CREATE_TIMEOUT_DEFAULT;
		}

		// MemcacheQ does not have a method to "create" a queue
		// queues are created upon sending a packet.
		// We cannot use the send() and receive() functions because those
		// depend on the current name.
		$result = $this->_cache->set($name, 'creating queue', 0, 15);
		$result = $this->_cache->get($name);

		$this->_queues[] = $name;

		return true;
	}

	/**
	 * Delete a queue and all of it's messages
	 *
	 * Returns false if the queue is not found, true if the queue exists
	 *
	 * @param  string  $name queue name
	 * @return boolean
	 * @throws Zend_Queue_Exception
	 */
	public function delete($name)
	{
		$response = $this->_sendCommand('delete ' . $name, array('DELETED', 'NOT_FOUND'), true);

		if (in_array('DELETED', $response)) {
			$key = array_search($name, $this->_queues);

			if ($key !== false) {
				unset($this->_queues[$key]);
			}
			return true;
		}

		return false;
	}

	/**
	 * Get an array of all available queues
	 *
	 * Not all adapters support getQueues(), use isSupported('getQueues')
	 * to determine if the adapter supports this feature.
	 *
	 * @return array
	 * @throws Zend_Queue_Exception
	 */
	public function getQueues()
	{
		$this->_queues = array();

		$response = $this->_sendCommand('stats queue', array('END'));

		foreach ($response as $i => $line) {
			$this->_queues[] = str_replace('STAT ', '', $line);
		}

		return $this->_queues;
	}

	/**
	 * Return the approximate number of messages in the queue
	 *
	 * @param  Zend_Queue $queue
	 * @return integer
	 * @throws Zend_Queue_Exception (not supported)
	 */
	public function count(Zend_Queue $queue=null)
	{
		require_once 'Zend/Queue/Exception.php';
		throw new Zend_Queue_Exception('count() is not supported in this adapter');
	}

	/********************************************************************
	 * Messsage management functions
	 *********************************************************************/

	/**
	 * Send a message to the queue
	 *
	 * @param  string     $message Message to send to the active queue
	 * @param  Zend_Queue $queue
	 * @return Zend_Queue_Message
	 * @throws Zend_Queue_Exception
	 */
	public function send($message, Zend_Queue $queue=null)
	{
		if ($queue === null) {
			$queue = $this->_queue;
		}

		if (!$this->isExists($queue->getName())) {
			require_once 'Zend/Queue/Exception.php';
			throw new Zend_Queue_Exception('Queue does not exist:' . $queue->getName());
		}

		$message = (string) $message;
		$data    = array(
            'message_id' => md5(uniqid(rand(), true)),
            'handle'     => null,
            'body'       => $message,
            'md5'        => md5($message),
		);

		$result = $this->_cache->set($queue->getName(), $message, 0, 0);
		if ($result === false) {
			require_once 'Zend/Queue/Exception.php';
			throw new Zend_Queue_Exception('failed to insert message into queue:' . $queue->getName());
		}

		$options = array(
            'queue' => $queue,
            'data'  => $data,
		);

		$classname = $queue->getMessageClass();
		if (!class_exists($classname)) {
			require_once 'Zend/Loader.php';
			Zend_Loader::loadClass($classname);
		}
		return new $classname($options);
	}

	/**
	 * Get messages in the queue
	 *
	 * @param  integer    $maxMessages  Maximum number of messages to return
	 * @param  integer    $timeout      Visibility timeout for these messages
	 * @param  Zend_Queue $queue
	 * @return Zend_Queue_Message_Iterator
	 * @throws Zend_Queue_Exception
	 */
	public function receive($maxMessages=null, $timeout=null, Zend_Queue $queue=null)
	{
		if ($maxMessages === null) {
			$maxMessages = 1;
		}

		if ($timeout === null) {
			$timeout = self::RECEIVE_TIMEOUT_DEFAULT;
		}
		if ($queue === null) {
			$queue = $this->_queue;
		}

		$msgs = array();
		if ($maxMessages > 0 ) {
			for ($i = 0; $i < $maxMessages; $i++) {
				$data = array(
                    'handle' => md5(uniqid(rand(), true)),
                    'body'   => $this->_cache->get($queue->getName()),
				);

				$msgs[] = $data;
			}
		}

		$options = array(
            'queue'        => $queue,
            'data'         => $msgs,
            'messageClass' => $queue->getMessageClass(),
		);

		$classname = $queue->getMessageSetClass();
		if (!class_exists($classname)) {
			require_once 'Zend/Loader.php';
			Zend_Loader::loadClass($classname);
		}
		return new $classname($options);
	}

	/**
	 * Delete a message from the queue
	 *
	 * Returns true if the message is deleted, false if the deletion is
	 * unsuccessful.
	 *
	 * @param  Zend_Queue_Message $message
	 * @return boolean
	 * @throws Zend_Queue_Exception (unsupported)
	 */
	public function deleteMessage(Zend_Queue_Message $message)
	{
		require_once 'Zend/Queue/Exception.php';
		throw new Zend_Queue_Exception('deleteMessage() is not supported in  ' . get_class($this));
	}

	/********************************************************************
	 * Supporting functions
	 *********************************************************************/

	/**
	 * Return a list of queue capabilities functions
	 *
	 * $array['function name'] = true or false
	 * true is supported, false is not supported.
	 *
	 * @param  string $name
	 * @return array
	 */
	public function getCapabilities()
	{
		return array(
            'create'        => true,
            'delete'        => true,
            'send'          => true,
            'receive'       => true,
            'deleteMessage' => false,
            'getQueues'     => true,
            'count'         => false,
            'isExists'      => true,
		);
	}

	/********************************************************************
	 * Functions that are not part of the Zend_Queue_Adapter_Abstract
	 *********************************************************************/

	/**
	 * sends a command to MemcacheQ
	 *
	 * The memcache functions by php cannot handle all types of requests
	 * supported by MemcacheQ
	 * Non-standard requests are handled by this function.
	 *
	 * @param  string  $command - command to send to memcacheQ
	 * @param  array   $terminator - strings to indicate end of memcacheQ response
	 * @param  boolean $include_term - include terminator in response
	 * @return array
	 * @throws Zend_Queue_Exception if connection cannot be opened
	 */
	protected function _sendCommand($command, array $terminator, $include_term=false)
	{
		if (!is_resource($this->_socket)) {
			$this->_socket = fsockopen($this->_host, $this->_port, $errno, $errstr, 10);
		}
		if ($this->_socket === false) {
			require_once 'Zend/Queue/Exception.php';
			throw new Zend_Queue_Exception("Could not open a connection to $this->_host:$this->_port errno=$errno : $errstr");
		}

		$response = array();

		$cmd = $command . self::EOL;
		fwrite($this->_socket, $cmd);

		$continue_reading = true;
		while (!feof($this->_socket) && $continue_reading) {
			$resp = trim(fgets($this->_socket, 1024));
			if (in_array($resp, $terminator)) {
				if ($include_term) {
					$response[] = $resp;
				}
				$continue_reading = false;
			} else {
				$response[] = $resp;
			}
		}

		return $response;
	}
}
